Analysis On The Aerodynamic Acoustic Characteristics Of Chevron Nozzle At Low Mach Number

Applied to aviation exhaust nozzle,chevron nozzle becomes the most popular technology of passive noise control, for its excellent performance on noise control,thrust loss,simple manufacturing. While the condition is changed to low mach number, research on aeroacoustics characteristics helps to control industrial noise.Experimental and numerical methods are combined to investigate the influence of different penetration and chevron count on jet flow field,vortex quantity field and distribution of turbulence intensity,noise spectrum,directivity. Using all these methods, the relationship between flow field and acoustic field is explored.Main research work in this paper includes:1. Aeroacoustics experiment devices are built, and chevron nozzles with different parameters are designed. Low speed noise elimination wind tunnel and pneumatic noise elimination room are the main parts of the experiment devices, chevron nozzles contain penetration and number;2. Time-resolved PIV crossed axial plan is carried out using seeding smoke combined with laser and CCD camera. Analysis on flow field,vortex quantity field and distribution of turbulence intensity is focused;3. The numerical computation study on both chevron nozzles and round nozzle is introduced and studied. With unstructured grid and proper calculation settings, numerical computation method can used for the comparison with experiment; 4. Far-field noise of chevron nozzles and round nozzle are measured using microphones. Without interrupting flow field, 18 points of measurement are fixed up to get the information of acoustic field.